The present invention relates broadly to a telephone circuit converter apparatus, and in particular to a low voltage two wire to four wire telephone circuit converter apparatus for use with a four wire, full duplex fiber optic voice transceiver.
In the prior art, voice and low speed data communications networks generally utilize two-wire trunks as the transmission medium. With the advent of complex long distance voice communication networks, it was necessary to utilize four-wire trunks as the individual segments of the over-all transmission path. These four-wire trunk systems provided communication paths of greater transmission efficiency and higher fidelity.
It is therefore highly desirable in high speed data communication systems to employ four-wire station-to-station connections. High speed data is presently transmitted over four-wire private lines which are connected, either directly between the transmitting station and the receiving station, or through manual switching centers which are provided for high speed data communication networks. While low speed data and voice communications may presently be handled over circuits containing both two-wire and four-wire trunks, this dual type of wiring combination is not suitable for high speed data transmission. In addition, separate switching centers are currently necessary for two-wire and four-wire trunk facilities. While the two-wire switching centers are used as originating and terminating switching centers, the four-wire switching centers are only used as intermediate toll switching centers. Since the four-wire switching centers are located at widely dispersed locations, they may also serve as toll centers for a large number of two-wire switching centers.
As the demand for high speed data communication increases, it is highly probable that customers will be located at a considerable distance from one another and from the four-wire station transmission facilities. Thus, it would be highly desirable to terminate and switch these four-wire facilities at the local two-wire switching centers that are close to the customer and currently serve the customer for voice and low speed data communications.